1. Field of the Invention
The present invention generally relates to an image-display system. The present invention particularly relates to an image-display system that includes image-display devices for displaying a plurality of images simultaneously, and to a user interface provided in an image-display system for allocating a document that includes a plurality of pages to image-display devices included in the image-display system.
2. Description of the Related Art
An image is enlarged by being displayed on a plurality of projectors in a presentation. In addition, a part of the image displayed on each of the projectors can have a high resolution. Further, by setting a plurality of image-display devices on a table, and then displaying images on the image-display devices, more information can be displayed at once on the image-display devices than on a single image-display device. Operation systems such as Windows 98 produced by Microsoft and Mac OS produced by Apple provide a function to use a plurality of image-display devices for displaying images. However, a plurality of video cards 12 must be added to a computer 10, the video cards 12 corresponding to respective image-display devices 14 that are connected to the computer 10 as shown in FIG. 1. Alternatively, special hardware similar to a video card that can connect a plurality of the image display devices 14 must be prepared in addition to the computer 10 and the image-display devices 14.
Additionally, there is software named VNC that displays an image displayed on a monitor of a first computer onto a monitor of a second computer through a network. This VNC is freeware created by Tristan Richard, Quentin Stafford-Fraser, Kenneth R. Wood, and Andy Hooper (Tristan Richard, Quentin Stafford-Fraser, Kenneth R. Wood, Andy Hooper, “Virtual Network Computing”, IEEE Internet Computing, Volume 2, Number 1, January/February 1998). The VNC enables fast update of an image displayed on the monitor of the second computer by transmitting raster data of an updated area on the monitor of the first computer and a command to replace a color of an evenly colored area on the monitor of the first computer, to the second computer.
As software installed in an image-display system that includes the computer 10 (a control device) and a plurality of the image-display devices 14, there exists a web browser such as the Internet Explorer produced by Microsoft. The image-display system including the web browser is called a hypertext-document display system, and displays a hypertext document wherein texts, still pictures, movies and sounds included in the document are linked to other related data called objects. The web browser obtains data in an HTML (HyperText Markup Language) format through a network by use of a HTTP protocol, or reads the data from a local disk. Subsequently, the web browser analyzes the obtained data, generates image data indicating contents of the obtained data, and displays the image data on a monitor. The web browser obtains new data in the HTML format from a linked address when a user clicks a mouse in a specific area that has been initially linked to other documents on a monitor, and then displays the new data as an image on the monitor. Additionally, an area called a tool bar provided on an HTML-data display screen displays two buttons, “forward” and “back”. The web browser can display the previous pages that have been displayed on the monitor by a user pressing the buttons “forward” and “back”.
Another image-display system is a system that uses a plurality of image-display devices. One of methods to use the image-display devices is to divide a large image into images, and then to display the images on the image-display devices. Another method, disclosed in Japanese Laid-Open Patent Application No. 9-81475, is to divide a document logically and then to display logically divided pages of the document. In this method, an LCD (Liquid Crystal Display) board is used as an image-display device. However, a CRT display and a projector may be substituted for the LCD board. Generally, a document includes a set of pages. Assuming each of the pages included in the document is displayed on one of the image-display devices, a user can switch from one page to another page intuitively by observing the pages displayed on the image-display devices simultaneously, or by changing a location of each of the image-display devices physically. A document created by use of a word processor is considered a series of pages in one dimension. The invention disclosed in Japanese Laid-Open Patent Application No. 9-81475 displays a plurality of the pages included in the document simultaneously on the image-display devices by transmitting files that include a plurality of the pages to a group of the image-display devices.
However, in hypertexts such as the HTML, each page includes links connected to other pages in addition to a link to the previous page and a link to the next page. Thus, there exist a plurality of pages connected to each page. In a case in which hypertexts that include complicated links to a plurality of pages are to be displayed on a plurality of image-display devices, a control device included in an image-display system cannot determine which page a user wants to display on each of the plurality of image-display devices only by transmitting the plurality of pages to the plurality of image-display devices. In such an environment, it is necessary to provide a user interface that relates a specific page in a document to a specific image-display device in an image-display system.